We are profoundly ignorant about the origins of language and have to content ourselves with more or less plausible speculations. We do not even know for certain when language arose, but it seems likely that it goes back to the earliest history of man, perhaps haft a million years ago. We have no direct evidence, but it seems probable that it took the earliest forms of human cooperation. In the Ice Ages of the Pleistocene(更新世) period, our earliest human ancestors established the Old Stone Age culture they made stone tools and, later, tools of bone, ivory, and antler they made fire and cooked their food they hunted big game, often by methods that called for considerable cooperation and coordination. As their material culture gradually developed, they became artists and drew pebbles as well as wonderful paintings of animals on the walls of caves. It is difficult to believe that the makers of these Paleolithic(旧石器时代的) cultures lacked the power of speech. It is a long step, admittedly, from other earliest flint weapons to the splendid spear of the late Stone Age: the first crude flints date back perhaps to 500,000 B.C., while the finest achievements of Old Stone Age man are later than 100,000 B. C. and in this period we can envisage a corresponding development of language, from the most primitive and limited language of the earliest human groups to a fully developed language in the flowering time of Old .Stone Age culture. How did language arise in the first place? There are many theories about this, based on various types of indirect evidence, such as the language of children, the language of primitive societies, the kinds of changes that have taken place in language in the course of recorded history, the behavior. of higher animals like chimpanzees, and the behavior. of people suffering from speech defects. These types of evidence may provide us with pointers, but they all suffer from limitations. When we consider the language of children, we haw to remember that their situations are quite different from those of our earliest human ancestors because the child, growing up in an environment where there is al- ready a fully developed language, is surrounded by adults who use that language and are teaching it to him. For example, it has been shown that the earliest words used by children are mainly the names of things and people ('doll,' 'spoon,' 'Mummy'), but this fact does not prove that the earliest words of primitive man were also the names of things and people. When the child learns the name of an object, he may then use it to express his wishes or demands. 'Doll!' often means,. 'Give me my doll!' or 'I've dropped my doll. Pick it up for me!' The child is us- ing language to get things done, and it is almost an accident of adult teaching that the words used to formulate the child's demands are mainly nouns instead of words like 'Bring!' 'Pick Up!' and so on. Theories of the origin of language include all of the following EXCEPT______.